Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
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Sat, 07 Mar 2026 09:00:00 +0000

Type Values Removed Values Added
Description Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
Title Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager
Weaknesses CWE-295
CWE-350
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-03-07T08:50:32.525Z

Reserved: 2026-01-21T19:40:25.776Z

Link: CVE-2026-24281

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-07T09:16:07.437

Modified: 2026-03-07T09:16:07.437

Link: CVE-2026-24281

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses